Snap device



July 24, 1962 G. vlEzzoLl 3,045,498 y SNAP DEVICE 1 Filed May 20, 1960 si* w n E El,

Glan Glo Y/zzz oL l 3,045,498 Patented VJuly 24, 1962 3,045,498 SNAP DEVICE Giorgio Vezzoli, Pavia, Italy, assignor to Societa Minelba s.r.l., Milan, Italy Filed May 20, 1960, Ser. No. 30,491 Claims priority, application Italy May 2), 1959 8 Claims. (Cl. 74--17.8)

'Ihe present invention relates to snap action devices, working when subjected to an outer force of a predetermined value, and adapted to perform immersed in liquid as well as gaseous iluid means, such as the atmosphere, and not to be inliuenced by the pressure changes of said fluid even though said changes arise suddenly and with a substantial value.

The device according to the present invention com prises essentially an element yielding resiliently when the outer force of a predetermined amount is acting thereon, said elementsurrounding a system made up-of a rigid element surrounded by segmental means blocking said rigid element in a prefixed position, said segmental means being adapted rto be displaced when subjected to said outer force, and because of the deformation of said resilient member, so as to allow the snap action movement of said mobile means when the forceV attains the predetermined value, this displacement of said mobile meansV bringing into operation other members or devices connected there, t0.

\` The principle of the present invention and the rangeoff its applications will be apparent in the following dis- ,closure of some embodiments of the present invention members of said snap action device according to the ,Y

present invention and its embodiment, -and more precisely: i

FIG. l is an axial section of the device and FIG. 2 is a plan sectional view on theV line A-B of FIG. l,

FIG. 3 is a sectional view like that of FIG. l concerning another embodiment of the snap action device, the` right hand half showing a variation with-respect to the left hand one. Y

FIG. 4 showspapsectional view through the axis of another form of realisation of the snap action device according to the present invention as applied to an electric contactor device.

The embodiment 'shown in FIGk l and FIG. 2 comi prises, as main elements, a movable piston shaped means 1, which has its widened upper head formed with a plurality of sloping surfaces, as clearly shown on the drawing. One of`- these surfaces, sloping downwardly, is in engagement relationship with some surfaces, correspondingly shaped, of segmental elements shown with reference numeral 2, and which are six in number in the embodiment herein illustrated. They are shaped as clearly shown on the drawing, and terminate with a very thin portion, which bears on a groove 3 of a stationary crown 4. The upper portion of the movable element 1, segmental elements 2 and the top portion of crown -3-are all of them surrounded and enclosed in a cap 5 of resilient material.

The operation of thesnap acton'device shown in FIGS. l and 2 is as follows: when on the snap action device top a force F of a predetermined value is applied, the elastic cap 5 allows an easy downward motion of the piston shaped mobile mem-ber 1, said displacement being allowed by segmental means 2 in that the pressure exerted by the sloping surface of element 1, contacting segmental means 2, causes these segmental means 2 to move outwardly, while rotating about their lower end which is engaged in groove 3 and expanding resilient cap 5, which has such a size as to allow said displacement.

When the innermost tip of segmental means 2 goes beyond the 'sloping surface of element 1, the piston shaped element 1 will be free to move downwardly speedily and suddenly, the resilient actuation by cap 5, which will bias segmental means 2 to engage into the top recess 6 of the head -of piston element 1, will improve the quick snap action movement of piston shaped element 1 while limiting in the meantime the displacement thereof.

On the other hand, when a sudden change of the pressure of the uid inrwhich said snap action device is immersed takes place, cap element 5 will be subjected to pressures such asr those shown by arrows p. These pressures exerting their action simultaneously on the head as well as sides of cap 5, then there would be no displacement of the inner members of the snap action device, because the action of said pressures p would compensate each other thus preventing the snap action device from operating at that moment.

FIG. 3 shows a modification of the snap action device illustrated in the preceding gures, and, in this case, ythe segmental means are replaced either by cylinders with one tip shaped and directed towards the inside and shown at 7 onrthe drawing, or by balls 8, said elements being i nengaged in grooves or seats provided in a stationary cylinders 7 or .balls 8 in the form of a resilient ring or `cylinder 10, which surrounds the portion where said movable elements 7 or 8 areplaced, whilst the device assembly is vagain enclosed in a resilient cap 11, which in this case may be much lighter as it has no more the purpose to bias cylinders 7 or balls 8 but has simply the task of forming a protection and a sealing action against ,the uid surrounding it, and of gathering and transmitting the eventual external pressure changes. In this case the head of the mobile piston shaped element 1 is formed with an enlarged portion 12, and the force F will act -thereon -so as to cause the snap action of the device. Indeed, when a force F of a predetermined amount is applied on the top plate 12 of themobile element 1', this latterwill bias cylinders 7 orfballs 8, which will be pushed awayV in a radial` direction, deforming the resilient retaining member 10, and allowing, when said displacement has reached a sufficient value, the sudden downward movement of the mobile piston shaped element 1' bringing about the desired snap action. I l

vInthis case too, after the snap action has taken place elements 7 or 3 go back to their original position, but engage in the top groove of mobile piston shaped 1.

In this case too the snap action device as illustrated is not sensitive to the pressure action exerted by the fluid said device is immersed in. In particular, when the top portion of the snap action device, covered with resilient cap 11 is immersed in air, a pressure wave, even though a substantial surge, which arises near the said device would not be able to make the device operate, which thence would not lose its charge and eiciency.

FIG. 4 represents diagrammatically an application of the snap action device, forming the object of the present invention, which has -been carried out in a manner like that shown in the igures previously described, to an electric contact control which may be used in many applications. As may be seen in FIG. 4, said control device comprises a mobile and rigid member 12, the cylindrically shaped lower end thereof being inserted and slidably disposed within a corresponding socket provided in a circular crown shaped element 14, on which segmental elements 16 are pivotally mounted at 15 and these elements 16 terminate at their top end wtih bosses having upper conical surfaces, the conicity thereof wholly corresponding to the conicity of the top portion of the mobile member 13. The mobile element 13 is provided at its inner end with an electric contact 20. The other electric contact 18 is fixed on a stationary member 17 of insulating material and mounted on the fixed crown element 14. Said contact 18 is connected to an electric conductor 18', while the metallic element 14 is grounded. The whole assembly is surrounded and enclosed within a resilient cap 22 of rubber or another similar resilient material, the lower edge thereof being anchored and xed as shown at 22', to the stationary crown 14, while at the top it is formed with a thickening 23 which forms the pressure plate for the application of the force which is to actuate the snap action device of the present invention.

The performance of the embodiment of the snap action device illustrated in FIG. 4 is the following: when a pressing force is exerted on the top portion 23 of cap 22, after the control device is placed at the required point, the downward stroke of said mobile piece 13 is prevented by the segmental elements 16 till the applied load reaches a predetermined value for which the resilient element holding the segmental elements 16 has been set. Then said segmental elements 16 turn around their relative pivots 15, moving away in a radial direction, since they overcome the elastic holding bias exerted by resilient element 22, and allow the free downward travel of mobile element 13. When, however, the wider portion of said mobile element 13 has gone beyond the tips of segmental elements 16, then these latter tend to close with a snapping action under the elastic force exerted on them by resilient element 22, this effect still more accelerating the downward travel of mobile element 13, and the electric contact 20 reaches suddenly the stationary contact 18, closing the electric circuit controlled by them.

The resilient member, which holds the segmental elements 16 in the position shown on the drawing, may be made up of a suitable resilient ring, as provided in the embodiment shown in FIG. 3. In this case the outer cap would work only as a protection means with regard to the inside of the snap action device, and for the task described for cap 11 of FIG. 3.

The elements such as 2 and 16 in FIGS. 1 and 4 respectively, and the band with the pin 7 or balls 8 of FIG. 3, constitute holding means surrounded by the side wall of the cup.

Of course, it will be apparent to those skilled in the art, that the applications of the snap action devices according to the present invention are not to be considered as being limited to that shown in FIG. 4. Therefore, the `constructional details of the snap action device as resulting its many applications as well as of the applications may be changed according to need without however departing from the scope of the present invention.

What I claim is:

l. A snap action device for operation in a fluid comprising a member movable between two positions and having a part on which a force can be exerted in a first direction to produce such movement from inoperative to operative position, holding means including; at least one element normally engaging with said member for holding it in inoperative position and movable in a second direction transverse to said rst direction to permit movement of the member, a base within which the member and element are movably mounted, and a cuplike cover of flexible material having its rim secured to the base and having its bottom overlying said part and its side wall surrounding said holding means and lying close enough to the holding means so as, when an increase in pressure in the iluid in which the device is enclosed occurs, to prevent sulcient movement of the element to allow movement of the member to operative position.

2. A device as claimed in claim 1 in which the cover is of resilient material and the side wall engages the element for normally holding the member in inoperative position.

3. A device as claimed in claim 1, in which the element is fulcrummed on the base.

4. A device as claimed in claim l, in which an elastic ring within the cover engages the element for normally holding the member in inoperative position.

5. A device as claimed in claim l, in which the element and the member each have two slanting surfaces meeting in an edge, the upper surface on the element engaging the lower surface on the member when the member is in inoperative position and the lower surface on the element engaging the upper surface on the member after the edges have passed each other to push the member towards operative position.

6. A device as claimed in claim 5, in which the cover is of resilient material and the side wall engages the element for normally holding the member in inoperative position.

7. A device as claimed in claim 6, in which the element is fulcrummed on the base.

8. A device as claimed in claim 1, in which the member and base carry electrical contacts engageable by movement of the member to operative position.

References Cited in the le of this patent UNITED STATES PATENTS 599,245 Merrill Feb. 15, 1898 831,745 Rice Sept. 25, 1906 983,610 Dooley Feb. 7, 1911 2,300,694 Overbeke Nov. 3, 1942 2,451,176 Schellman Oct. 12, 1948 2,505,548 Hutt Apr. 25, 1950 2,936,651 McCleary May 17, 1960 FOREIGN PATENTS 352,644 France Aug. 16, 1905 

